Improving the Sustainability of Steel Sheet Pile Bulkheads

Steel sheet pile bulkheads are widely used for waterfront structures and shoreline stabilization. Due to their smooth surface and reflective nature they provide limited habitat opportunities for aquatic species. One example is Cleveland’s Cuyahoga River navigation channel. The Cuyahoga River navigation channel has been transformed from a natural system to an important passageway for maritime commerce but is now a daunting corridor for transient fish. For fish, the ability to migrate upriver to spawn as adults and downriver to return to Lake Erie as juveniles is critical to their survival. The navigation channel poses challenges due to lack of habitat, limited food sources, low water velocity, and at certain times of the year, low dissolved oxygen and high water temperatures. Much of the navigable portion of river (5 miles/8 km) is lined on both sides with steel sheet pile bulkheads. The 27 foot (8.3m) dredged channel and the vertical sheet pile bulkheads provide very limited opportunities for habitat reestablishment. Since 2006, the U.S. Army Corps of Engineers (USACOE) has been developing, testing and implementing technologies to create habitat for larval and juvenile fish while maintaining the channel for navigation. Building on lessons learned from earlier work, the objective of the Green Bulkhead Project is to understand the altered system dynamics of the river, and use the principles of biomimicry to develop a replicable and durable solution for creating functional habitat for larval fish along the aging steel bulkheads. The project team has identified desired functions (shelter and nourishment) and defined project context, which includes designing the retrofit to withstand large sediment loads, passing vessels and ice within the channel. The conceptual design stage looked to biological models for inspiration. The selected alternative is a hanging steel basket that can be attached to the inner flanges of the bulkhead sheets. The baskets can be filled with a variety of natural materials to mimic natural river bank functions. The baskets have been designed to meet the difficult conditions in the navigation channel. Prototypes of the habitat enhancement baskets were installed in the fall of 2015.